1. Field of the Invention
The present invention relates to a hydraulic pump used together with an automotive power steering apparatus.
2. Description of the Prior Art
In a conventional hydraulic pump for use in a power steering apparatus, an intake hole communicating with a pump reservoir is arranged in separate relationship with a low pressure hole communicating with a flow control valve. Accordingly, pump suction efficiency is not completely sufficient. Furthermore, a drive shaft for rotating a pump rotor is supported by a pump housing and a pressure plate adjacent to the pump rotor. Therefore, the bearing bores formed in the pump housing and the pressure plate for the support of the drive shaft have to be machined in precisely coaxial relationship, and the thickness of the pressure plate has to be large with the result of a difficulty in a compact-sized hydraulic pump.
Furthermore, in the conventional hydraulic pump, a pump discharge port communicating with the power steering apparatus is communicated with the flow volume control valve in intersected relationship, so that the pump housing has to provide a projection to form the discharge port with the result of a difficulty in a compact-sized hydraulic pump.